Organic molecules that weigh more than
100,000 Dalton's are referred to as macromolecules.

These macromolecules are constructed of
smaller units called polymers. These polymers are subdivided
into their basic units called monomers.

Polymers account for the molecular
uniqueness of organisms. Twenty amino acids are responsible for
all forms of life. These amino acids form every conceivable
protein known to man.

Making and breaking of
polymers:

Dehydration synthesis: is an
anabolic process by which two molecules are chemically bonded
through the use of enzymes and a loss of water.

glucose + glucose + enzyme =
maltose + water + enzyme.

Hydrolysis: is a catabolic process
by which the bond between monomers are broken by the enzyme and
the addition of water.

sucrose + water + enzyme =
glucose + fructose + enzyme.

Carbohydrates: include sugars and
their polymers. They include monosaccharides
disaccharides,and polysaccharides. The
monosaccharide is a monomer, the disaccharide is a polymer,and
the polysaccharides are macromolecules.

Disaccharides: These are double
sugars with the formula
C12H22O11.
Notice that one molecule of water is missing from the formula.
The covalent bond holding the two monomers together is called a
1-4 or 1-2 glycoside linkage. Examples: sucrose = glucose +
fructose. maltose = glucose + glucose, and lactose =
glucose + galactose.

Polysaccharides: The basic formula
is (
C6H10O5)n. These are macromolecules capable of
acting as structural or storage molecules.

Storage Polysaccharides: Starch is a
plant storage polysaccharide that is composed entirely of
glucose joined by @1-4 glycoside linkages. amylose is the
simplest form of starch. amylopectin is more complex and is
branched. Glycogen is an animal starch stored in the liver and
muscles of vertebrates.It is more
highly branched than amylopectin.

Structural Polysaccharides:
Cellulose and chitin are examples of structural
polysaccharides.

Cellulose is the most abundant organic
compound on earth. It is made of glucose, like starch, but they
differ in the type of 1-4 linkage. Instead of an @ linkage as
in starch cellulose contains a B 1-4 linkage.

This causes the polysaccharide to take on a
step arrangement and not a linear one like in
starch.

Enzymes find it difficult to brake the B
1-4 linkage.

Lipids: A group of polymers that
have one characteristic in common, they do not mix with water.
They are hydrophobic. Some important groups are fats,
phospholipids, and steroids.

Fats: are large molecules composed
of 2 types of monomers, glycerol ( an alcohol containing 3
carbons)and 3 fatty acid molecules. The
bond connecting the glycerol and fatty acids in the fat
molecule is called an ester bond. There are two types of fatty
acids: saturated and unsaturated. The saturated fatty acids do
not contain any double bonds between the carbons, while the
unsaturated fatty acids contain one or more double bonds
between the carbons. These double bonds cut down on the number
of hydrogen atoms that can be attached to the carbon in the
molecule. This causes the molecule to bend or kink at each of
the double bond sites.

Characteristics of Fats:

Saturated

Unsaturated

1. solid at room
temperature

1. liquid at room
temperature

2. found mostly in
animals

2. found mostly in
plants

3. no double bonds between
carbons

3. double bonds found between
carbons

Function of fats: acts as insulation in
higher vertebrates, serves as an energy storage source 1g.=9
Kcal of energy, and shock absorber for internal
organs.

Phospholipids: structurally related
to fats but contain 2 fatty acids and one molecule of
phosphate. These molecules are found making up the plasma
membrane of cells. They exhibit a polar and non polar quality.
The phosphate group is hydrophilic while the fatty acid area is
hydrophobic.

Steroids: Lipids characterized by a
carbon skeleton of 4 fused rings. Cholesterol is an important
steroid found in all animal tissue. Plants do not contain
cholesterol. Cholesterol functions in many ways: it is a
precursor from which many of the bodies steroids are
constructed from. It also adds strength to the plasma membrane
in animal cells.

Proteins: macromolecules that make
up 50% of the dry weight of most cells.

There are 20 different amino acids. Each
amino acid has an optical isomer. The left amino acid is the
functional one. The D- amino acid only rarely function.
Proteins are formed by bonding amino acids together. The bond
formed is called a peptide bond.

Protein conformation: refers to the three
dimensional shape of a protein molecule. This shape is
important to its function. If the conformation is changed, even
slightly , then the function of the protein
changes.

Levels of Protein
structure:

1. Primary: refers to the unique
sequence of amino acids in the protein. All proteins have a
special sequence of amino acids, this sequence is derived from
the cell's DNA.

2. Secondary : the coiling or
bending of the polypeptide into sheets is referred to the
proteins secondary structure. alpha helix or a beta pleated
sheet are the basic forms of this level. They can exist
separately or jointly in a protein.

3. Tertiary: The folding back of a
molecule upon itself and held together by disulfide bridges and
hydrogen bonds. This adds to the proteins
stability.

4. Quaternary: Complex structure
formed by the interaction of 2 or more polypeptide
chains.

Nucleic Acids: DNA and
RNA.

Nucleotides: monomers that come
together to form a nucleic acid. They contain either a ribose
or deoxyribose sugar ( ribose has one more oxygen in its
molecule),

Deoxyribose Sugar

phosphate, and a nitrogenous base (purine =
guanine or adenine, pyrimidine = cytosine, thymine , or
uracil). Pyrimidines are constructed of a single ring while
purines are characterized by a double ring. The nucleotides are
joined together by phosphodiester bonds.

Base pairing rule. A-T, A-U, C-G. DNA has a
double helix shape, while most RNA is single
stranded.